1. Technical Field
The present invention generally relates to a system and method for screening liquid compositions such as fuels and lubricating oil compositions.
2. Description of the Related Art
It is critical to the success of many companies that products can be efficiently sampled and screened. For example, in the case of a lubricating oil composition, the lubricating oils may be subjected to a demanding environment during use in an internal combustion engine. The environment results in the oil suffering oxidation which is catalyzed by the presence of impurity species in the oil such as, for example, iron compounds, and is also promoted by the elevated temperatures experienced by the oil during use. The catalyzed oxidation of the oil not only contributes to the formation of corrosive oxidation products and sludge in the oil but can also cause the viscosity of the oil to increase or even solidify.
In addition, deposits can adversely affect the operation of the engine. For example, deposits can form on the areas of an engine contacted by lubricating oil compositions. Deposits that form in high temperature areas of an engine can lead to mild engine damage such as piston and cylinder scuffing, leading to problems such as e.g. increased engine emissions. In extreme cases, such deposits can result in, e.g., valve sticking and ring sticking, leading to possible catastrophic damage of the engine. Deposits in low temperature areas of the engine such as the cranckcase typically take the form of sludge. Sludge formation can reduce the cooling efficiency of an engine, and in severe cases can impede the operation of pumps.
Areas of a fuel intake system can also be burdened by the formation of deposits. Typical areas include carburetor ports, the throttle body and venturies, engine intake valves, etc. For example, deposits on the carburetor throttle body and venturies increase the fuel to air ratio of the gas mixture to the combustion chamber thereby increasing the amount of unburned hydrocarbon and carbon monoxide discharged from the chamber. The high fuel-air ratio also reduces the gas mileage obtainable from the vehicle.
When deposits on the engine intake valves get sufficiently heavy, they can restrict the gas mixture flow into the combustion chamber. This restriction starves the engine of air and fuel and results in a loss of power. Deposits on the valves also increase the probability of valve failure due to burning and improper valve seating. In addition, these deposits may break off and enter the combustion chamber possibly resulting in mechanical damage to the piston, piston rings, engine head, etc.
The formation of these deposits can be inhibited as well as removed by incorporating an active detergent into, for example, the fuel. These detergents function to cleanse these deposit-prone areas of the harmful deposits, thereby enhancing engine performance and longevity.
Lubricating oil and lubricating oil additive suppliers as well as fuel and fuel additive suppliers are therefore constantly performing research to discover new materials that are improved in these aspects. In addition, there are several ASTM engine Sequence tests which must be run to achieve passing results in order to certify candidate engine lubricant formulations and fuel formulations that meet API (American Petroleum Institute) and ILSAC (International Lubricant Standardization and Approval Committee) standards. However, these tests are very expensive and time consuming.
As a result, bench test methods can be used to assess the performance of any new lubricating oil composition or fuel composition prior to it being recommended to a potential user. A good bench test is therefore a crucial component of new product development, quality control, i.e., fitness for use, and product improvement. For example, these bench tests are also a useful marketing tool in trying to convince a potential user to employ an existing lubricating oil composition or an existing user to employ an improved lubricating oil composition. They serve to demonstrate to a customer that a particular lubricating oil composition will perform effectively in their specific process. Therefore, it would be desirable to provide a laboratory bench test that can simulate the oxidation and detergency performance of a new lubricating oil composition or fuel composition under operating conditions.
One bench test that evaluates the oxidation and detergency tendency of a lubricating oil is the “panel coker” test, e.g., Federal Test Method Standard 791B-3462. In the panel coker test, approximately 100 g of oil is preheated in a sump and then intermittently projected by means of a rotating oil stirrer onto an aluminum test plate heated at a high temperature for a period of 48 hours. The amount of deposit on the aluminum plate is weighed at the end of the 48 hours.
Accordingly, there is a need for an improved system and method for screening liquid compositions such as lubricating oil compositions.